Venting device for electrolytic condensers



p 2 1937- J. POITRAS 2,093,574

,YsuTmGpEvIcE FOR ELECTROLYTIC CONDENSERS Filed larch 26, 1934 zzmuuIIlllllll I.

u I I l l l I i I I l IINVENTOR JOSEPH .P TR/9S ATTORNEY r'atented Sept.21, 1937 PATENT OFFICE 'VENTING DEVICE FOR ELEC'IBOLYTIO CONDENSEBSJoseph A. Poitras, Fort Lee, N. J., assignor to Solar ManufacturingCorporation, a corporation of New York Application March 26, 1934,Serial No. 717,348

4 Claim.

This invention relates to improvements in electrolytic devices, such aselectrolytic condensers, rectifiers or the like, comprising film-formingelectrodes.

5 In such devices, use is made of the film-forming eii'ect exhibited bycertain metals, like aluminum, tantalum or magnesium, which when placedin suitable electrolytes, upon application of the proper voltage, arecovered with a film. Such l films consist of partially hydrated aluminumor tantalum oxide and have a unidirectional conductivity for theelectrical current.

'Ihese condensers are used for different purposes, one of theirprincipal uses being in filter 15 circuits to eliminate the alternatingcurrent ripples from rectified currents. However, it should be wellunderstood that my invention is not at all limited to such purposes andapplications, but, as will become apparent, has a much wider scope 20which will reach beyond that of electrolytic condcnsers in general.

In electrolytic condensers, such as are used for the above statedpurpose, only one of the electrodes, namely the anodefis required to beof 25 film-forming metal,preferredly aluminum.

The cathode which, as a rule, also forms the container of the condenser,is either made of a metal which does not exhibit film formation, likecopper or nickel, or even of aluminumalso, which, where 30 it comes intodirect contact with the electrolyte, can be plated with chromium or thelike. Such containers which simultaneously form the cathode, can beshaped in difl'erent ways,-as a rule they consist. substantially of atubular mantle 35 which at one end is crimped over a dished lid, or therim of the latter is beaded over the edge of the former, as shown in thepresent illustration, while the other end forms a hermetically sealedseam around an insulating bushing, supporting the anode member. In mycopending application, Serial No. 71mm filed July 24, 193,4, 1 haveshown the total construction of such a condenser, still as the presentinvention does not lay 45 any claims to any parts of such construction,.but

rather to asingle feature serving a special function, yet to beexplained, all such details are omitted in the accompanying drawing, andthe fiagode member itself is only indicated by its oute. It is alsoimmaterial for. the present inventive concept how the inner electrode oranode is formed, whether in the form of single spaced plates or a singleplate, rolled into a spiral, or 55 finally as is shown in my co-pendlngapplication mentioned above.

In either case the inner space between the anode and the cathodecontainer is filled by the electrolyte solution, preferredly up to abovethe top rim of the anode plate, to prevent sparking over as well ascorrosion in consequence of the sparking over, or any corona effect.This electrolyte filler may either be in a liquid or a semiliquidcondition, and for aluminum electrodes a variety of acid or sodiumelectrolytic solutions are in use, as for example, sodium sulphate,potassium permanganate, ammonium chromate, cyanide of potassium, sodiumsilicate (semi-liquid) ammonium phosphate or citrate and finally, as themost commonly used: borax. Tantalum condensers use mostly an acidelectrolyte, like sulphuric acid, or ammonium chloride, borate orsulphate or mixtures of sulphuric acid with other salts. In all cases,however, there occurs, as a result of the electrolytic action, acontinuous more or less copious formation of gas bubbles,

mostly of oxygen (in the case of cyanide of potassium of nitrogen), asnot all the oxygen is used in the formation of the film or forms waterwith the nascent hydrogen. For this accumulating gas pressure an outletmust be provided, especial- 1y as in addition the electrolytic action isaccompanied by a development of heat, and to provide such an outlet in anovel and improved form, is the general purpose of the presentinvention.

I am aware that various schemes have been devised and triedin practicetodeaerize" electrolytic cells and thereby prevent eventual explosions",with spilling of acid and other accidents, but these safety devices,though effective when p of-N3 131:!v constructed and handled, do nottake a sufficient care of the human element and are as me not foolproof.Consequently they will occasionally fail, besides having otherdrawbacks. Sometimes, where the lid consists of insulating material ofconsiderable thickness, the gas vent consists of a hole drilled throughthe lid which for shipment or before installation is plugged with wax toprevent spilling of the electrolyte. when the condenser is put intoservice the wax plug is supposed to be removed or punctured to permitescape of the gases. Or a thin sheet of rubber is-cemented over the venthole which also should be punctured before service commences. In anotherconstruction the vent hole device comprises a conical rubber nipple, thetip of which is to be perforated by a needle hole which ordinarily osesup but opens when the gas pressure is sumciently great, or the rubbernipple has a weakened portion which is supposed to rupture r I under theforce of gas pressure. These latter two devices oftenfail under abnormaloperating conditions; i. e. when a great volume of gas is suddenlydeveloped. Moreover all these devices depend upon human precaution.While it is necessary that they should be kept hermetically closedduring shipment and handling, it is presuming too muchthat all buyers ofsuch devices, among Whom there are necessarily many amateurs who installtheir own radio hookups, will not neglect to provide proper perforationsbefore connecting the condensers. Such an oversight is liable to happeneven to those skilled in the art.

Even so, if the perforations are in time provided, 7

there remains the danger, especially in portable sets, that, should theassembled apparatus be brought into a lateral or overturned position,the electrolyte may seep out of the now permanently open vent hole,which in addition may have been made too large. This is another drawbackwhich is successfully prevented in applicant's improved I "ventingdevice.

It is therefore among the objects of the present invention to provide adegassing or venting device for gas containers which from the startworks automatically.

A further object of my invention is to provide an automatic degassing orventing device for electrolytic condensers which from the start is in a80 working condition.

Another corollary object is to provide such an automatic venting devicewhich while always being in an efilcient working condition, is hermetically closed during shipment or handling.

85 Another object of my invention is to provide a venting device whichautomatically opens without rupture of any rubber diaphragm wheneversumcient gas pressure is applied to it and automatically andhermetically closes again.

A further object is to provide a venting device of the kind describedwhich, when open, provides an ample exit for a sudden excess gaspressure.

A further object of my invention is to provide a venting device forelectrolytic condensers which .45 can be shipped ready for installationand immediate service.

A further object of my invention is to provide a venting device forelectrolytic condensers which does not require any manual preparation,previous to active and automatic service and is therefore ,foolproof.

Other more specific objects and advantages of my device will appear asthe nature of the improvements is better understood, the inventionconsisting substantially in the novel arrangement and correlation ofinstrumentalities herein fully described and illustrated in theaccompanying drawing wherein similar reference characters are used todescribe corresponding parts throughout 0 the several views and thenfinally pointed out and specifically definedand indicated in theappended claims.

The disclosure made the basis of exemplifying the present inventiveconcept suggests a practical 5 embodiment thereof, but the invention isnot to be restricted to the exact details of this disclosure, and thelatter therefore is to be understood from an illustrative, rather than arestrictive standpoint. In the accompanying drawing- Fig 1 is a top viewof a condenser, in which one form of my invention is embodied;

Fig. 2 is a cross-section along line 2-2 of Fig. 1; Fig. 3 is a detailview in perspective, partly I broken, showing the valve cap and thegasket over scribed.

the gas escapes in cross section, with the clamp for the resilientmember partly turned to better disclose its shape;

Fig. 4 is a top view of a modified form;

Fig. 5 is a cross-section along line 55 of Fig. 4;

Fig. 6 is a detail view in perspective, showing the star-shaped springwhich gives resiliency to the valve lid;

Fig. 7 shows a third modification, embodying the principles of myinvention, partly in crosssection;

Fig. 8 illustrates the valve body, shown in full in the previous figure,in cross-section.

Referring more in detail to the different views, III indicates thecylindrical mantle of the container of the condenser in the differentmodifications, and I I designates the dished lid, inserted into one endof this mantle. In most cases this is the top end, the terminalconnections being provided at the bottom end, as shown more fully in mycopending application, although such an arrangement is not indispensableand might as well be reversed, if so desired. The container, includingthe dished lid, is usually made of aluminum, as aforesaid, and the anodeelement I2 which is only outlined, is, of course, of film-formingmaterial, aluminum or tantalum.

The dished lid II has an annular flange Ila which is slightly taperedtoward the inside and the upper edge IIb is crimped over the extreme endof the tubular mantle Ill, which is spun inwardly to secure a tight fitwith the lid. The electrolyte which fills the space between thecontainer and the inner electrode and also any empty spaces within theportions of the latter, is indicated by I3. 3

The middle portion of the dished member II (see Figs. 1 and 2) is raisedto form a cylindrical head I I which has a bigger central opening I5 andseveral smaller perforations I 6, concentrically located around thelatter, through which gas can 40 escape. Over these gas holes isprovided a pliable 1; gasket I'|, made of soft rubber or leather or anequivalent material, and this loose gasket is kept in place by amushroom-shaped lid I8, clamped over said gasket by a resilient member,anchored on the underside of the cylindrical head I 4. The resilientmember comprises a saddle-like anchor -I 9, made of a metal strip, bentin inverted U form, and a resilient cushion 20, which may consist eitherof a very soft rubber ring supported on the projecting ends of theanchor I9, or even of alight coil spring (not especially illustrated)applied in the same way. The depressed central portion of the lid I8 iscoupled to the top of the anchor I9 through opening I5 by a rivet 2|,and it will be clear from the description that ordinarily the gas holesI6 are kept closed by the tension of the resilient member 20, pressingthe lid l8 and gasket I1 against them, but that any excess gas pressurewill evenly raise the gasket against the resiliency of the anchor, untilenough gas has escaped. 1 The modification shownin Figs. 4 and 5 differsfrom the first device principally by the shape of the anchor I9u. andthe absence of a special resilient cushion. The anchor itself is aresilient washer, having the shape of a three-pointed star, as shownseparately in Fig. 6. The device functions in a similar way as the onepreviously. de-

The third modification, illustrated in Figs. 7 and 8, shows the wholeventing device countersunk in the top lid 22 and consisting principallyof non-metallic valve parts.

The dished lid 22 has a middle portion in the 15 form of a depressedfunnel-shaped cup 22a. The conical portion of the funnel can either besmooth or be provided with an annular offset to better seat the valvebody, and the vent holes 23 are provided in this conical portion. At theend, protruding toward, the interior of the container, the

funnel ends in a short cylindrical nozzle 22b.

In this cylindrical nozzle and partly on the conical slope is seated thevalve body P, represent 2lb. The other part 25 consists of a rather flatsaucer-shaped disk which fits into the part 2! by means of a male andfemale connection. A short cylindrical plug 250, integral with the disk,fits into a close fitting recess 140 in the inner end of the cylindricalneck 24a. Opposite the male connection part 25c is a recess 25d forcountersinking the slotted buttonhead of the tap screw 2.6 which passesthrough a central perforation in the member 25 and is threaded tightlyinto the member 24, as plainly shown in Fig. 8. A little metal washer(which advantageously may. be a resilient split washer, to preventspontaneous loosening of the screw) may be inserted underneath the headof the screw. The saucer-shaped flange 25a, when the screw 26 istightened, should press tightly against the vent holes 23, and to insurea tight fit, the slope of the flange 25a should be somewhat less thanthat of the funnel portion 2211., so that by tightening the screw theslight clearance over the neck portion 24a, between the flange 25a andthe funnel 22a is eliminated.

It is evident that any excessive gas pressure reaching the saucer-shapedflange 25a through the vent holes 23, temporarily lifts up the flangewhich, as so as the pressure is released, will hermetically lose theholes again. It is equally evident that normally, when there is no gaspressure, the resilient part 25a or in the formerly describedconstructions, the gaskets I'I effectively seal the vent holes, nomatter in what position the condensers are held or are being shipped;also that, to install the latter, no perforations or unscrewing oi.shipping caps or'the like, are necessary.

In accordance with the provisions of the patent statutes, I havedescribed my invention, but I desire it understood that it is notconfined to the particular form shown and described, the same beingmerely illustrative, and that the invention may be carried out in otherways without departing from the spirit of my invention, and therefore Iclaim broadly the right to employ all equivalent instrumentalitiescomingwithin the scope of the appended claims, and by means of which,objects of my invention are attained and new results accompllshed, as itis obvious that the particular embodiments herein shown and describedare only some of many that may be employed to attain these objects andaccomplish these results.

Having thus described my invention, what I "claim and desire to secureby Letters Patent, is:

1. A self-closing relief valve, adapted to release gas from anelectrolytic condenser, provided with a multiplicity of concentricallyarranged vent holes in its container wall, said valve comprising anannular gasket, seated over said vent holes, a cover enclosing saidannular gasket, and resilient means to normally press said cover againstsaid gasket, closing the vent holes hermetically.

2. A self-closing relief valve, adapted to release gas from anelectrolytic condenser, provided witha multiplicity of concentricallyarranged vent holes in its container wall, said valve comprising anannular gasket, seated over said vent holes, a dished cap inverted oversaid annular gasket, and a resilient anchor positioned in the center oisaid cap and adapted to yieldingly anchor the dished cap with the gasketto the container wall.

3. A self -closing automatic relief valve, adapted to relieve thesurplus gas pressure in an electrolytic condenser, provided with aventin a cupped portion of its container wall, said valve comprising apliable gasket adapted to yieldingly close said vent, a cover clampedover said gasket and a spring member positioned on the opposite innerside of the container, coupled to the cover through an aperture in thecontainer and adapted to anchor the cover and gasket resiliently to thecontainer-wall.

4. A self-closing automatic relief valve, adapted to relieve the surplusgas pressure in an electrolytic condenser, provided with a multiplicityof vent holes in circular arrangement through its container wall, saidvalve comprising a pliableannular member adapted to cover the vent holesfrom the outside, a resilient member seated on solid unperforated partsof the container wall on the inside, and clamping means to couple theoutside annular member to'the inside resilient member in such a way thatthe gas pressure can lift the outside member away from the vent holesagainst the resiliency of the inside member.

JOSEPH A. POI'I'RAS.

